Dear yt user,
I try to use Generic UnicGrid Data (256^3 gas density cube + position
of particle that is subset of a huge simulation).
It is preliminary work, but I still have some questions.
1. In order to set density unit as cgs, I made following script:
......
data = dict(density = (map, "g/cm**3")) #map is 256^3 density data array
bbox = np.array([[0., boxsize], [0., boxsize], [0.,boxsize]])
ds = load_uniform_grid(data, data['density'][0].shape, 3.086e24,
bbox=bbox, nprocs=4)
.....
Then, I got the following error message:
Traceback (most recent call last):
File "cutout2.py", line 62, in <module>
ds = load_uniform_grid(data, data['density'][0].shape, 3.086e24,
bbox=bbox, nprocs=4)
File "/Users/jhchoi/common/lib/python2.7/site-packages/yt-3.0dev-py2.7-macosx-10.4-x86_64.egg/yt/frontends/stream/data_structures.py",
line 461, in load_uniform_grid
psize = get_psize(np.array(data[key].shape), nprocs)
AttributeError: 'tuple' object has no attribute 'shape'
Hence, I modify "data = dict(density = (map, "g/cm**3"))" --> "data =
dict(density = map)" and it work.
If this is the case, how can I define the density unit and show it
when I make Slice/Projection?
In addition, I would like to know how I can set the unit in Generic
UnicGrid Data in general?
The length unit can be provide to script in load_uniform_grid(...
3.086e24 ....) but I do not know how to set other units.
2. When I add particle information as follow:
.....
npart = 100000 # number of particles
data = dict(density = map,
number_of_particles = npart,
particle_position_x = posx,
particle_position_y = posy,
particle_position_z = posz)
bbox = np.array([[0., boxsize], [0., boxsize], [0.,boxsize]])
ds = load_uniform_grid(data, data['density'][0].shape, 3.086e24,
bbox=bbox, nprocs=4)
...
I got the following error message:
Traceback (most recent call last):
File "cutout.py", line 107, in <module>
ds = load_uniform_grid(data, data['density'][0].shape, 3.086e24,
bbox=bbox, nprocs=4)
File "/Users/jhchoi/common/lib/python2.7/site-packages/yt-3.0dev-py2.7-macosx-10.4-x86_64.egg/yt/frontends/stream/data_structures.py",
line 519, in load_uniform_grid
assign_particle_data(spf, pdata)
File "/Users/jhchoi/common/lib/python2.7/site-packages/yt-3.0dev-py2.7-macosx-10.4-x86_64.egg/yt/frontends/stream/data_structures.py",
line 371, in assign_particle_data
pdata.pop("number_of_particles")
KeyError: 'number_of_particles'
So, I change "number_of_particles = npart," --> "number_of_particles =
100000," and it works.
How could it happen?
3. Can I do halo finder (hop/fof) using the above particle data?
Or, what information do I need to provide to do grouping?
In this case, how can I set the units and linking length?
4. Can I make particle distribution to particle data like
data['Dark_Matter_position_x']?
This process will allow me additional analysis such as profile and
obtaining total value.
I may ask too many for new tool, but it will help a lot to use yt for
general data set.
Thank you,
Junhwan

I'd like to try using the PerspectiveCamera instead of the normal
orthographic Camera. My script renders fine with Camera(), but I thought
that I should be able to just change Camera() to PerspectiveCamera() and it
should render with the perspective. Instead, I get an empty rendering --
is there something else one needs to do to use the PerspectiveCamera rather
than just changing the class name but otherwise keeping the argument list
the same?
Mike
--
Michael Zingale
Associate Professor
Dept. of Physics & Astronomy • Stony Brook University • Stony Brook, NY
11794-3800
*phone*: 631-632-8225
*e-mail*: Michael.Zingale(a)stonybrook.edu
*web*: http://www.astro.sunysb.edu/mzingale

Hi folks,
I'm trying to make a projection of an Enzo dataset using yt-3, showing the
maximum level along the line of sight. This command:
ProjectionPlot(pf,"x","grid_level",weight_field=None,data_source=reg,width=(0.25,'unitary')).save()
definitely seems to make projections of grid levels, but I'm not convinced
that it is the maximum level along the LOS. Is there a better way to do
this?
Thanks!
--Brian

Is there a way to set the background color for projection plots? I'd like
to set it to be black instead of white, which I assume is the default.
Thanks,
Andrew E.
--
Graduate Student
Columbia University
Department of Astronomy

Hi all,
I am trying to make a nice volume rendering, and am having some trouble.
My camera commands are:
tf = ColorTransferFunction((-29,-24))
tf.add_layers(8,w=0.1,colormap="Hue Sat Value 2")
tf.sample_colormap(-26.5,w=0.02,colormap="Hue Sat Value 2")
cam = pf.h.camera([0.0,2.,1.8],[0.0,-1.0,-0.2],4.0,512,tf)
cam.show()
I will attach the image, also (v11). First, when I use add_layers, can I
get yt to print out WHERE the layers are? Second, but related, when I just
use add_layers I only see the higher density gas. I have to add
sample_colormap to see lower density gas (the blue stuff). Compare v11 to
v6 to see what I am talking about.
Thanks!
Stephanie

I'm trying to show the transfer function on a volume render. Plotting a
velocity component, I set the transfer function with 4 Gaussians all with
the same width. The range of the transfer function is -1.e7 to 1.e7, but
for some reason, when output, the upper label in the colorbar is not 1.e7
but a bit lower (9.92e6). I am not sure where the code is that draws this,
and I am confused why it is not setting the tick at 1.e7. It gets the
bottom tick right.
Here's an image:
http://bender.astro.sunysb.edu/random/test_0000.png
and the script:
http://bender.astro.sunysb.edu/random/vol_rotate.py
any pointers are appreciated.
Mike
--
Michael Zingale
Associate Professor
Dept. of Physics & Astronomy • Stony Brook University • Stony Brook, NY
11794-3800
*phone*: 631-632-8225
*e-mail*: Michael.Zingale(a)stonybrook.edu
*web*: http://www.astro.sunysb.edu/mzingale

Hi yt,
I have a pretty simple question that I ought to know the answer to - how
do I extract the actual values in the field_list or derived_field_list of a
ds?
For example, I have a field: ('PartType0', 'Coordinates'),
but printing something like pf[('PartType0','Coordinates')] doesn't return
the list of particle type 0 coordinates (or anything for that matter). Do
I have to access this through a pf.all_data() command somehow?
Thanks
-desika

Hi yt users,
I wanted to know if it is possible somehow to make plots (projections and slices) of a subregion of the domain, e.g. I define a sphere like :
sph= pf.h.sphere(center=[0,0,0], radius=(100,'pc’))
Now I want to plot the projection of the density of that region in the x axis:
slc = SlicePlot(sph, 'x', 'dens')
But then I get the following error:
AttributeError: 'AMRSphere' object has no attribute 'domain_width'
thanks for your help,
Juan
_____________________________
Juan Camilo Ibañez Mejia
Department of Astrophysics
American Museum of Natural History
+1-212-313-7435
jibanezmejia(a)amnh.org<mailto:jibanezmejia@amnh.org>
_____________________________